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Figure 3.
Figure 3. Cofactor and K+-binding sites in human E1b. (a)
Schematic representation of the cofactor-binding site. Gln112-a
and protein ligands of the magnesium ion have been omitted for
clarity. (b) Potassium site 1 (a subunit). The metal stabilizes
a loop involved in cofactor binding. The metal ion is bound by
two mainchain carbonyl groups and by the sidechains of Ser161-a,
Thr166-a and Gln167-a. The sidechain of Leu164-a and the
mainchain carbonyl group of Ser162-a make direct contact with
the ThDP cofactor. (c) Potassium site 2 (b subunit). The metal
binding at this site stabilizes regions in the b subunit at the
interface with the small C-terminal domain in the a subunit. The
metal is octahedrally coordinated mainly by mainchain carbonyl
groups and interacts favorably with the C-terminal end of a
helix dipole as indicated. Several sidechains indicated by an
asterisk have been omitted for clarity. This figure was made
with LIGPLOT [50], MOLSCRIPT [48] and the Raster3D suite [49].
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